A 19-year-old female patient with Charcot-Marie-Tooth disease (CMTD) exhibited delayed puberty related to primary ovarian failure. A biopsy of the ovary revealed the presence of a few small follicles and overall atrophy of the gland. The type of CMTD affecting this patient may be a X-linked dominant (CMTX1) form. In CMTX1, mutations in the gene encoding the gap junction protein connexin 32 (Cx 32) appear to be the cause of peripheral neuropathy. Gap junctions are, however, also important for the normal growth of ovarian follicles, a complex event that requires extensive cell-cell communication. It is thus possible that a defective Cx 32 protein might be related to the ovarian failure observed in our patient. Whether Cx 32 is expressed in the primate ovary is not known. In the rat ovary, Cx 43 appears the major, if not the only gap junction protein expressed by granulosa cells, oocytes and thecal cells, while in mice and cattle Cx 32 has been found in the oocyte-cumulus complex. Immunohistochemical examination demonstrated the existence of Cx 43 immunostaining in granulosa cells of human ovaries as well as in granulosa cells, thecal cells and oocytes of fetal, immature and adult monkey ovaries. Follicles devoid of Cx 43 immunoreactivity were also observed. Cx 32-immunoreactivity was detected in a subpopulation of granulosa cells of small and large follicles in both monkey and human ovaries, as well as in monkey oocytes. In contrast, no Cx 32 was detected in the ovarian biopsy of our patient. Expression of the Cx 32 gene in the nonhuman primate ovary was further assessed by RT-PCR. Thus, our results show for the first time that both Cx 43 and Cx 32 are expressed in primate ovarian follicles. Since gap junctional cell-cell communication is required for the growth and function of follicles, it is conceivable that a mutational defect of Cx 32 in CMTX1 may interfere with normal ovarian 640020pment.